1. Field of the Invention
The present invention relates to a tubular doorknob, and more particularly to a tubular doorknob with adjustment devices for firmly mounting the tubular doorknob in a door.
2. Description of Related Art
With reference to FIG. 9, tubular doorknobs are mounted in doors (93) to hold doors (93) shut and unlatch and open doors (93). A conventional tubular doorknob comprises an outside handle assembly (91), an inside handle assembly (92) and a latch assembly (not numbered). The tubular doorknob is mounted in a knob hole (931), a transverse latch hole (not shown) and two knob mounting holes (932) formed in a door (93). The transverse latch hole communicates with the knob hole (931). The two knob mounting holes (932) are formed through the door (93) on diametrically opposite sides of the knob hole (931). The latch assembly is mounted in the transverse latch hole, extends into the knob hole (931), connects the outside handle assembly (91) to the inside handle assembly (92) and partially holds the outside handle assembly (91) and the inside handle assembly (92) in the knob hole (931). Since mounting a tubular doorknob in a door (93) is common knowledge for people skilled in this field, a complete description of mounting the tubular doorknob in a door (93) is not provided.
An outside bracket (911), an inside bracket (921) and fasteners such as bolts (94) are used to align and securely hold the outside handle assembly (91) and the inside handle assembly (92) in the knob hole (931) in a door (93). The outside bracket (911) has a central hole (not numbered), two mounting tubes (912) and an inner flange (not numbered). The flange protrudes from the central hole. Each mounting tube (912) protrudes from the outside bracket (911) toward the inside handle assembly (92), has an internal thread (not numbered) and is mounted in the corresponding knob mounting holes (932) in the door (93).
The inside bracket (921) has a central hole (not numbered), two mounting holes (922) and an inner flange (not numbered). The inner flange is formed around the central hole. The two mounting holes (922) respectively correspond to the mounting tubes (912) extending from the outside bracket (911).
Fasteners, such as bolts (94), attach the inside bracket (921) to the outside bracket (912) on opposites sides of the door (93) around the knob hole (931). Each bolt (94) has a distal end (not numbered), a proximal end (not numbered), an enlarged head (not numbered) and an external thread (not numbered). The enlarged head is formed on the proximal end of the bolt (94), and the external thread is formed around the distal end of the bolt (94). The distal ends of the bolts (94) pass respectively through the mounting holes (922) in the inside bracket (921) and into the knob mounting holes (932) and screw into the mounting tubes (912). Screwing the bolts (94) into the mounting tubes (912) draws the outside bracket (911) and the inside bracket (921) together against the door (93). The tubular doorknob is held axially in place in the door (93) by the flanges on the inside bracket (921) and the outside bracket (911).
However, the conventional tubular doorknob has some shortcomings.
First, the tubular doorknob cannot be held precisely in the knob hole (931) in the door (93). Because the knob hole (931) is always defined with a tolerance so the tubular doorknob can be easily mounted in the knob hole (931), only the flanges on the outside bracket (911) and the inside bracket (921) and the connect ion with the latch assembly hold the tubular doorknob in place radially in the knob hole (931). However, extensive use gradually reduces the ability of the flanges to hold the tubular knob. The tubular doorknob will eventually spin or slip in the knob hole (931). The movement or rotation of the tubular doorknob in the knob hole (931) may keep the tubular doorknob from operating properly.
Second, the conventional tubular doorknob only has two mounting tubes (912) to hold the tubular doorknob axially in the knob hole (931). As the flanges on the inside bracket (921) and the outside bracket (911) deform and the two bolts (94) in the mounting tubes (912) loosen, the tubular doorknob loosens in the door (93). With the tubular doorknob loose, a thief can more easily jimmy the latch assembly and open the locked door (93).
To overcome the shortcomings, the present invention provides an improved tubular doorknob with adjustment devices for firmly mounting the tubular doorknob in a door to mitigate or obviate the aforementioned problems.
The main objective of the invention is to provide a tubular doorknob with adjustment devices for firmly mounting the tubular doorknob in a door.
To achieve this objective, the tubular doorknob with the adjustment devices for firmly mounting the tubular doorknob in a door has an inside bracket, an outside bracket and adjustment devices. The outside bracket has an inside side, an outside side, two connecting wings, two passages, two screw holes and an adjustment device. The connecting wings protrude from diametrically opposite sides of the inside side of the outside bracket. The passages are respectively defined through the connecting wings and correspond to each other. The screw holes are defined through the outside bracket from the outside side and communicate respectively with the passages. The adjustment device is mounted in the outside-bracket and has two sliding blocks and two adjustment screws. The sliding blocks are slidably mounted in the passages. The adjustment screws are screwed into the screw holes to push the sliding blocks against a surface of a doorknob hole in the door. The inside bracket has a similar configuration. Consequently, the adjustment devices will firmly hold the tubular doorknob in the door.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.